How to unload a package without restarting R - r

Question

I'd like to unload a package without having to restart R (mostly because restarting R as I try out different, conflicting packages is getting frustrating, but conceivably this could be used in a program to use one function and then another--although namespace referencing is probably a better idea for that use).
?library doesn't show any options that would unload a package.
There is a suggestion that detach can unload package, but the following both fail:
detach(vegan)
Error in detach(vegan) : invalid name argument
detach("vegan")
Error in detach("vegan") : invalid name argument
So how do I unload a package?

Answer 1

Try this (see ?detach for more details):
detach("package:vegan", unload=TRUE)
It is possible to have multiple versions of a package loaded at once (for example, if you have a development version and a stable version in different libraries). To guarantee that all copies are detached, use this function.
detach_package <- function(pkg, character.only = FALSE)
{
if(!character.only)
{
pkg <- deparse(substitute(pkg))
}
search_item <- paste("package", pkg, sep = ":")
while(search_item %in% search())
{
detach(search_item, unload = TRUE, character.only = TRUE)
}
}
Usage is, for example
detach_package(vegan)
or
detach_package("vegan", TRUE)

Answer 2

You can also use the unloadNamespace command, as in:
unloadNamespace("sqldf")
The function detaches the namespace prior to unloading it.

Answer 3

You can uncheck the checkbox button in RStudio (packages).

Answer 4

I tried what kohske wrote as an answer and I got error again, so I did some search and found this which worked for me (R 3.0.2):
require(splines) # package
detach(package:splines)
or also
library(splines)
pkg <- "package:splines"
detach(pkg, character.only = TRUE)

Answer 5

When you are going back and forth between scripts it may only sometimes be necessary to unload a package. Here's a simple IF statement that will prevent warnings that would appear if you tried to unload a package that was not currently loaded.
if("package:vegan" %in% search()) detach("package:vegan", unload=TRUE)
Including this at the top of a script might be helpful.
I hope that makes your day!

Answer 6

detach(package:PackageName) works and there is no need to use quotes.

Answer 7

Another option is
devtools::unload("your-package")
This apparently also deals with the issue of registered S3 methods that are not removed with unloadNamespace()

Answer 8

You can try all you want to remove a package (and all the dependencies it brought in alongside) using unloadNamespace() but the memory footprint will still persist. And no, detach("package:,packageName", unload=TRUE, force = TRUE) will not work either.
From a fresh new console or Session > Restart R check memory with the pryr package:
pryr::mem_used()
# 40.6 MB ## This will depend on which packages are loaded obviously (can also fluctuate a bit after the decimal)
Check my sessionInfo()
R version 3.6.1 (2019-07-05)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 17763)
Matrix products: default
locale:
[1] LC_COLLATE=English_Canada.1252 LC_CTYPE=English_Canada.1252 LC_MONETARY=English_Canada.1252 LC_NUMERIC=C
[5] LC_TIME=English_Canada.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
loaded via a namespace (and not attached):
[1] compiler_3.6.1 pryr_0.1.4 magrittr_1.5 tools_3.6.1 Rcpp_1.0.3 stringi_1.4.3 codetools_0.2-16 stringr_1.4.0
[9] packrat_0.5.0
Let's load the Seurat package and check the new memory footprint:
library(Seurat)
pryr::mem_used()
# 172 MB ## Likely to change in the future but just to give you an idea
Let's use unloadNamespace() to remove everything:
unloadNamespace("Seurat")
unloadNamespace("ape")
unloadNamespace("cluster")
unloadNamespace("cowplot")
unloadNamespace("ROCR")
unloadNamespace("gplots")
unloadNamespace("caTools")
unloadNamespace("bitops")
unloadNamespace("fitdistrplus")
unloadNamespace("RColorBrewer")
unloadNamespace("sctransform")
unloadNamespace("future.apply")
unloadNamespace("future")
unloadNamespace("plotly")
unloadNamespace("ggrepel")
unloadNamespace("ggridges")
unloadNamespace("ggplot2")
unloadNamespace("gridExtra")
unloadNamespace("gtable")
unloadNamespace("uwot")
unloadNamespace("irlba")
unloadNamespace("leiden")
unloadNamespace("reticulate")
unloadNamespace("rsvd")
unloadNamespace("survival")
unloadNamespace("Matrix")
unloadNamespace("nlme")
unloadNamespace("lmtest")
unloadNamespace("zoo")
unloadNamespace("metap")
unloadNamespace("lattice")
unloadNamespace("grid")
unloadNamespace("httr")
unloadNamespace("ica")
unloadNamespace("igraph")
unloadNamespace("irlba")
unloadNamespace("KernSmooth")
unloadNamespace("leiden")
unloadNamespace("MASS")
unloadNamespace("pbapply")
unloadNamespace("plotly")
unloadNamespace("png")
unloadNamespace("RANN")
unloadNamespace("RcppAnnoy")
unloadNamespace("tidyr")
unloadNamespace("dplyr")
unloadNamespace("tibble")
unloadNamespace("RANN")
unloadNamespace("tidyselect")
unloadNamespace("purrr")
unloadNamespace("htmlwidgets")
unloadNamespace("htmltools")
unloadNamespace("lifecycle")
unloadNamespace("pillar")
unloadNamespace("vctrs")
unloadNamespace("rlang")
unloadNamespace("Rtsne")
unloadNamespace("SDMTools")
unloadNamespace("Rdpack")
unloadNamespace("bibtex")
unloadNamespace("tsne")
unloadNamespace("backports")
unloadNamespace("R6")
unloadNamespace("lazyeval")
unloadNamespace("scales")
unloadNamespace("munsell")
unloadNamespace("colorspace")
unloadNamespace("npsurv")
unloadNamespace("compiler")
unloadNamespace("digest")
unloadNamespace("R.utils")
unloadNamespace("pkgconfig")
unloadNamespace("gbRd")
unloadNamespace("parallel")
unloadNamespace("gdata")
unloadNamespace("listenv")
unloadNamespace("crayon")
unloadNamespace("splines")
unloadNamespace("zeallot")
unloadNamespace("reshape")
unloadNamespace("glue")
unloadNamespace("lsei")
unloadNamespace("RcppParallel")
unloadNamespace("data.table")
unloadNamespace("viridisLite")
unloadNamespace("globals")
Now check sessionInfo():
R version 3.6.1 (2019-07-05)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 17763)
Matrix products: default
locale:
[1] LC_COLLATE=English_Canada.1252 LC_CTYPE=English_Canada.1252 LC_MONETARY=English_Canada.1252 LC_NUMERIC=C
[5] LC_TIME=English_Canada.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
loaded via a namespace (and not attached):
[1] tools_3.6.1 stringr_1.4.0 rstudioapi_0.10 pryr_0.1.4 jsonlite_1.6 gtools_3.8.1 R.oo_1.22.0
[8] magrittr_1.5 Rcpp_1.0.3 R.methodsS3_1.7.1 stringi_1.4.3 plyr_1.8.4 reshape2_1.4.3 codetools_0.2-16
[15] packrat_0.5.0 assertthat_0.2.1
Check the memory footprint:
pryr::mem_used()
# 173 MB
Link to screen-cast demonstration

Answer 9

Note also that you can only use unload() once. If you use it a second time without rerunning library(), y'll get the not very informative error message invalid 'name' argument:
library(vegan)
#> Loading required package: permute
#> Loading required package: lattice
#> This is vegan 2.5-6
detach("package:vegan", unload=TRUE)
detach("package:vegan", unload=TRUE)
#> Error in detach("package:vegan", unload = TRUE): invalid 'name' argument
Created on 2020-05-09 by the reprex package (v0.3.0)

Answer 10

I would like to add an alternative solution. This solution does not directly answer your question on unloading a package but, IMHO, provides a cleaner alternative to achieve your desired goal, which I understand, is broadly concerned with avoiding name conflicts and trying different functions, as stated:
mostly because restarting R as I try out different, conflicting packages is getting frustrating, but conceivably this could be used in a program to use one function and then another--although namespace referencing is probably a better idea for that use
Solution
Function with_package offered via the withr package offers the possibility to:
attache a package to the search path, executes the code, then removes the package from the search path. The package namespace is not unloaded, however.
Example
library(withr)
with_package("ggplot2", {
ggplot(mtcars) + geom_point(aes(wt, hp))
})
# Calling geom_point outside withr context
exists("geom_point")
# [1] FALSE
geom_point used in the example is not accessible from the global namespace. I reckon it may be a cleaner way of handling conflicts than loading and unloading packages.

Answer 11

Just go to OUTPUT window, then click on Packages icon (it is located between Plot and Help icons). Remove "tick / check mark" from the package you wanted be unload.
For again using the package just put a "tick or Check mark" in front of package or use :
library (lme4)

Answer 12

Connected with #tjebo answer.
TL;DR
Please use pkgload:::unload instead of devtools::unload as they are the same function (1 to 1) and pkgload is a much lighter package (nr of dependencies). devtools simply reexporting the pkgload:::unload function.
Unfortunately devtools is a huge dependency (as devtools has a lot of own dependencies), which is more development stage targeted. So if you want to use the unload function in your own package or you care about library size please remember to use pkgload:::unload instead of devtools::unload. devtools simply reexporting the pkgload:::unload function.
Please check the footer of the devtools::unload function to quickly confirm the reexport or go to the github repo
> devtools::unload
function (package = pkg_name(), quiet = FALSE)
{
if (package == "compiler") {
oldEnable <- compiler::enableJIT(0)
if (oldEnable != 0) {
warning("JIT automatically disabled when unloading the compiler.")
}
}
if (!package %in% loadedNamespaces()) {
stop("Package ", package, " not found in loaded packages or namespaces")
}
unregister_methods(package)
unloaded <- tryCatch({
unloadNamespace(package)
TRUE
}, error = function(e) FALSE)
if (!unloaded) {
unload_pkg_env(package)
unregister_namespace(package)
}
clear_cache()
unload_dll(package)
}
<bytecode: 0x11a763280>
<environment: namespace:pkgload>